The Spanish word 'gordo' meaning 'fat' comes from the Latin word 'gurdus', which meant 'heavy, thick, or clumsy'. The meaning evolved from describing something generally heavy or thick to specifically referring to having excess body fat. The word underwent a simple phonetic change from Latin 'gurdus' to Spanish 'gordo', with the 'u' becoming an 'o'.

Some common Spanish words derived from the same root include 'gordura' (fatness), 'engordar' (to fatten), and 'gordito/a' (chubby, a diminutive form often used affectionately). These words all maintain the core meaning related to fatness or thickness.

While there aren't any common English words directly related to 'gordo', English speakers might find it helpful to think of words like 'girth' or 'girthy' which, while not etymologically related, share a similar meaning of thickness or roundness. The Latin 'gurdus' didn't pass into English, but understanding its meaning of 'heavy' or 'thick' can help remember the Spanish word's meaning.